Continuously-operating shrinking machines have been in existence for about thirty years, and they are generally implemented in the form of a tunnel oven serving to shrink respective sleeves of heat-shrink plastics material engaged on articles which are placed on a conveyor belt forming the bottom of the shrinking tunnel. As each article travels on the conveyor belt from an upstream end towards a downstream end of the tunnel oven, the sleeve engaged on each article softens and then shrinks onto said article.
Very many techniques have already been implemented for controlling the anamorphic distortion of patterns printed on the sleeve during shrinking of said sleeve onto the article, and also for controlling the quality of sleeve shrinkage, which sleeve must be free from any curling or other imperfections on leaving the tunnel oven.
Amongst the numerous patent documents stemming from the Applicant, particular reference can be made to the following: FR-A-2 588 828, FR-A-2 634 274, FR-A-2 758 387, FR-A-2 797 944, and U.S. Pat. No. 5,031,298.
The various machines that have been made in this way are dedicated solely to industrial use in which it is desired to place sleeves on articles traveling at as high a rate of throughput as possible, and then to shrink the sleeves onto the associated articles, with the steps taking place continuously and solely in the presence of knowledgeable professionals.
A new need is now appearing that is associated with personalizing articles, and in particular bottles, with this being performed at the point of sale, leaving the consumer with the widest possible latitude in selecting a sleeve of desired appearance for shrinking onto an article. Unfortunately, machines of the above-described type are completely unsuitable for on-demand use by an average consumer who knows nothing about shrinkage phenomena.
There thus exists a need for a technique that is both simple and effective in enabling sleeves to be heat-shrunk individually and on demand by any ordinary consumer.
People in the profession have thus investigated how to make a small heat-shrink machine in the form of a small tunnel oven having an entrance where a consumer can place an article coated in a selected sleeve, and having an outlet from which the consumer can recover said article fitted with said sleeve shrunk onto it.
Unfortunately, it turns out that designing such machines of small dimensions is more difficult than was expected insofar as the articles concerned and the corresponding sleeves can vary to a very large extent.
In particular, a given article can be conditioned at temperatures that vary very greatly depending on the point of sale. This wide range of temperatures for the walls of articles has the effect of considerably modifying the conditions under which heat-shrink sleeves shrink onto said articles. It will naturally also be understood that the size of the article, and in particular variations in the section of such articles, likewise has a considerable effect on shrinkage conditions insofar as the amount of shrinkage required can vary considerably between the top and the bottom of the article. Finally, the thickness and the nature (polyethylene terephthalate (PET), polystyrene (PS), recyclable or not recyclable) of the film constituting the sleeve to be shrunk on the article can also vary and thus modify shrinkage conditions.
There thus exists an urgent need for a shrinkage technique which is both simple to implement and well adapted to on-demand use by ordinary consumers without the consumer needing to be concerned with making any adjustments as a function of the selected article and/or sleeve.
Ideally, a shrinkage technique should be made available suitable for being implemented under a very wide variety of conditions, in particular concerning the temperature at which the articles are conditioned prior to being covered in a heat-shrink sleeve.